This application claims the benefit of the Indian application No. 192/Del/2001 filed Feb. 27, 2001.
1. Field of the Invention
The present invention relates to automobile clutches in general and more particularly to pivot point release load adjuster assembly for use in a pull type angle spring clutch pressure plate assembly.
2. Background of the Invention
Clutches are well known mechanisms used in automobiles, which are devices adapted to typically connect a driven means and a rotational power source. The rotational power source is usually the crankshaft of an automobile engine. A clutch device is having an engaged position and a disengaged position. Typically a plurality of springs is used to move the clutch pedal from an engaged position to a disengaged position. The plurality of springs requires a high magnitude of force to be exerted on the clutch pedal for arriving at the disengaged position. Consequently the operator of an automobile vehicle is required to exert a high amount of pressure on the clutch pedal frequently at the time of changing gears resulting in discomfort and fatigue after continuous driving for long durations. There are many examples of prior art pedal pressure minimizing clutch devices, but most of them involve complex and expensive mechanisms. These are prone to wear and tear thus subject to premature failure. Efforts to minimize the release load on the clutch pedal while maintaining a higher clamp load with a view to arrive at a better driving comfort have been going on and this objective has been well recognized and pursued continuously over the years.
The principle of using thrust springs at an angle to provide clamp load in clutches has been made applicable in many of the prior art pull type clutch devices. In pull type clutches employing thrust springs, a load is applied to the end of a lever so that in the release position the spring load is contained between the levers and the cover. The geometry changes as the clutch is released giving a change in the axial effort. Since the springs are located at each end, the constraints on the geometry together with the spring rate determines what changes in the angular load can be achieved. Applying this principle, spring loaded pull type clutch devices have been used to arrive at desired rates in the angular loads. However there are limitations in the known devices, necessitating further efforts to minimize the pedal pressure to a more comfortable level.
In the past, it has been well known to construct a clutch pressure plate assembly employing angle springs. Identical arrangements providing mechanical constructions directed to using thrust springs at an angle to provide clamp load in clutches can be found in U.S. Pat. No. 4,034,836, U.S. Pat. No. 4,157,749, U.S. Pat. No. 4,760,906, U.S. Pat. No. 4,936,432, U.S. Pat. No. 5,067,602, U.S. Pat. No. RE 34, 105, and U.S. Pat. No. 5,373,927.
The arrangement shown in U.S. Pat. No. 4,034,836 provides for an improved connection for the release of levers. The improvement provides for opposed pivot and bearing portions on the levers with longitudinally extending ribs wherein the pivot portion is radially spaced. A sharp xe2x80x9cknife edgexe2x80x9d engages the pivot axis, the lug coacting to have a restraint so that the xe2x80x9cknife edgexe2x80x9d is maintained in contact with the pivot axis during the pivotal movement. The construction shown in U.S. Pat. No. 4,157,749 is identical to the above. These arrangements are structurally different from the disclosure made herein.
The construction shown in U.S. Pat. No. 4,760,906 is directed to an arrangement wherein three springs are circumferentially spaced equidistant about a release collar having radially extending ramped surfaces against which the assister springs engage and react. When the release collar is moved axially relative to the clutch cover, the assister springs are tilted away from the radial position. The arrangement shown in U.S. Pat. No. 4,936,432 is also an improvement in the construction of assister springs wherein spring seats are formed with the cover having V-shaped cross sections. The engagement spring seats are provided to pivotably pilot engagement springs for the clutch. In U.S. Pat. No. 5,067,602 the objective of the construction is to prevent excessive relative rotation, for which a plurality of protrusions are formed on the release sleeve retainer. In U.S. Pat. No. 5,373,927 the sleeve member is having an outwardly extending circumferential flange. The angled springs along with a plurality of axially extending spring members make the spring collector move towards the flange. All these arrangements are substantially different from the construction disclosed in the present invention.
The present invention relates to pivot point release load adjuster assembly for use in a pull type angle spring clutch pressure plate assembly wherein a novel assembly has been brought out to give greater flexibility in varying the axial load and in turn the release load to any desired configuration. A pin means and a cradle means have been devised so as to enable a swiveling movement of the cradle means on which the housing end of the pressure springs are mounted. The pin means is connected to the housing of the clutch assembly and the swiveling end of the pin means is having a pivoted contact surface on the cradle on which the springs are swivelingly mounted. This swiveling mechanism helps in obtaining the desired pivot point at a desired distance away from the spring seat on the swiveling end. The possibility of achieving the pivot point at such desired point away from the spring seat results in an increase in the lever ratio, consequently the release load is decreased and the pedal pressure is lowered. The goal of the present invention is therefore to bring down the pedal pressure to the desired minimum level thereby achieving better driving comfort.
Pressure springs are mounted on the pressure spring seat means on the sleeve retainer end. Pressure spring seat means have been provided on the release sleeve retainer with push pin means to help the pressure spring move in either direction.
Release sleeve retainer pin means are connected to the release sleeve retainer. The cradle has been provided on the housing end to help move the pressure springs as and when activations are made to disengage the clutch. Pressure spring seat means and release lever retainer pin means are used to keep the pressure springs axially in location as and when wear takes place on the pressure plate or any of the related parts thereof. A push type adjusting assembly has been used to adjust the setting height of clutches in the vehicles in the assembled condition. A replaceable brake disc has been provided to brake the clutch RPM.